UI Convertors

Contributing UI Converters

A UI Converter sits between the ui component and the record, a data convertor sits between the database and the record. Servoy ships by default one that redirects the conversion to script methods but it can also be contriuted by a Java Servoy client plugin, .

To do this, the plugin class implementing the IClientPlugin (see Implement the Plugin Interface) must also implement interface IUIConverterProvider to produce IUIConverter instances in the getUIConverters() method. A UI converter class implementing the IUIConverter interface has to implement the following three methods that will be displayed in the Edit text format property dialog:

• convertFromObject() Convert from UI value to dataprovider value

• convertToObject() Converts from dataprovider value to UI value

• getToObjectType() The UI data type (so the resulting type of the convertToObject()), being one of the IColumnTypes constants: TEXT, INTEGER, NUMBER, DATETIME or MEDIA

A UI converter class can define properties in the getDefaultProperties() method, which will be displayed in the Edit text format property dialog as well.

The dataprovider types that the UI converter supports are to be specified in the getSupportedDataproviderTypes() method. The implemented UI converters returned by the getUIConverters() method of the plugin class implementing the IUIConverterProvider interface will be then checked by the plugin manager which will add them to the list of Servoy UI converters.

Example

This is an example of a plugin that delivers a converter from joda time (which has support for time persiods) to java-util-date (which is supported by Servoy UI elements) time.

class MyUIConvertorPlugin implements IClientPlugin, IUIConverterProvider
{
    private static final IUIConverter[] UI_CONVERTERS = new IUIConverter[] { JodaToDateConverter.INSTANCE };

    public IUIConverter[] getUIConverters()
    {
        return UI_CONVERTERS;
    }
}

class NrToJodaConverter implements ITypedColumnConverter
{
 public static final NrToJodaConverter INSTANCE = new NrToJodaConverter();
 
 public Object convertToObject(Map<String, String> props, int column_type, Object dbvalue) throws Exception
 {
     if (dbvalue == null)
     {
         return null;
     }
     return new DateTime(Utils.getAsLong(dbvalue));
 }
 
 public Object convertFromObject(Map<String, String> props, int column_type, Object obj) throws Exception
 {
     if (obj instanceof DateTime)
     {
         return Long.valueOf(((DateTime)obj).getMillis());
     }
     return obj; // or throw an exception
 }

 public Map<String, String> getDefaultProperties()
 {
     return null;
 }
 public int[] getSupportedColumnTypes()
 {
     return new int[] { IColumnTypes.INTEGER };
 }
 public String getName()
 {
     return getClass().getSimpleName();
 }
 
 public int getToObjectType(Map<String, String> props)
 {
     // Servoy does not understand joda time natively.
     return IColumnTypes.MEDIA;
 }
}

class JodaToDateConverter implements IUIConverter
{
 public static final JodaToDateConverter INSTANCE = new JodaToDateConverter();
 
 public Object convertFromObject(Map<String, String> props, int input_type, Object converted) throws Exception
 {
     if (converted instanceof Date)
     {
         return new DateTime(((Date)converted).getTime());
     }
     return converted; // or return null or throw an exception
 }

 public Object convertToObject(Map<String, String> props, int input_type, Object input) throws Exception
 {
     if (input instanceof DateTime)
     {
        return new Date(((DateTime)input).getMillis());
     }
    return input; // or return null or throw an exception
 }
 
 public Map<String, String> getDefaultProperties()
 {
    return null;
 }
 
 public int[] getSupportedDataproviderTypes()
 {
     // Servoy does not understand joda time natively, therefore the dataprovider type will be MEDIA.
    return new int[] { IColumnTypes.MEDIA };
 }
 
 public String getName()
 {
    return getClass().getSimpleName();
 }
 
 public int getToObjectType(Map<String, String> props)
 {
    return IColumnTypes.DATETIME;
 }
}